Thermo-reversibly gelled colloidal suspensions and a process for making the same

Abstract

Disclosed is a thermoreversible synthesis of a new type of material made by embedding a colloidal population within a thermo-reversibly gelled polymer. The polymer may be a physically cross-linked PVA hydrogel. PVA hydrogels are non-toxic, biocompatible, mechanically robust, and elastic. The present invention TGCCA diffraction is similar to that of photo-polymerized PCCA. The present invention TGCCA can be irreversibly covalently cross-linked using glutaraldehyde. The cross-linked TGCCA can be made responsive to chemical stimuli by functionalizing the hydrogel hydroxyl groups. The diffraction of carboxyl or amine functionalized TGCCA was monitored as a function of the pH and determined diffraction wavelengths titrate with the pKa of the functional group. It was also demonstrated that TGCCA could be fabricated in arbitrarily large volumes and shapes. The present invention method fabricates inexpensive homogenously diffracting chemically modifiable TGCCA.

1 . A colloidal composition comprising a population of substantially monodispersed polymeric colloidal particles embedded within a thermo-reversibly gelled polymer, wherein the population of substantially monodispersed polymeric colloidal particles has an average diameter from about 30 nanometers to about 3000 nanometers. 
   
   
       2 . The colloidal composition of  claim 1 , wherein the population of substantially monodispersed polymeric colloidal particles has a coefficient of variation of particle diameter of about 25% or less. 
   
   
       3 . The colloidal composition of  claim 2 , wherein the population of substantially monodispersed polymeric colloidal particles has a coefficient of variation of particle diameter of about 10% or less. 
   
   
       4 . The colloidal composition of  claim 2 , wherein the population of substantially monodispersed polymeric colloidal particles are forming a crystalline colloidal array. 
   
   
       5 . The colloidal composition of  claim 1 , further comprising an aqueous solution. 
   
   
       6 . The colloidal composition of  claim 5 , wherein the aqueous solution has a specific conductance of less than about 1×10 −5  S·m −1 . 
   
   
       7 . The colloidal composition of  claim 5 , wherein the aqueous solution includes a co-dispersant. 
   
   
       8 . The colloidal composition of  claim 7 , wherein the co-dispersant is selected from the group consisting of dimethylsulfoxide, glycerine, ethylene glycol, propylene glycol and triethylene glycol. 
   
   
       9 . The colloidal composition of  claim 5 , wherein the aqueous solution includes a sugar. 
   
   
       10 . The colloidal composition of  claim 1 , wherein the thermo-reversibly gelled polymer comprises partially hydrolyzed poly(vinyl)acetate. 
   
   
       11 . The colloidal composition of  claim 10 , wherein the thermo-reversibly gelled polymer comprises poly(vinyl) acetate hydrolyzed to an extent greater than 80%. 
   
   
       12 . The colloidal composition of  claim 11 , wherein the thermo-reversibly gelled polymer comprises poly(vinyl) acetate hydrolyzed to an extent greater than 87%. 
   
   
       13 . The colloidal composition of  claim 1  wherein the polymer is comprised of a polymer including the [vinyl alcohol] repeat unit. 
   
   
       14 . The colloidal composition of  claim 1  wherein the population of substantially monodispersed polymeric colloidal particles has an average diameter from about 50 nanometers to about 800 nanometers. 
   
   
       15 . A product selected from the group consisting of sensor materials, optical filters, coatings, color shifting additives, paint additives, cosmetic additives, sound insulation or colloidal storage approaches comprising a colloidal composition of  claim 1 . 
   
   
       16 . A method of embedding a colloidal composition within a thermo-reversibly gelled polymer comprising:
 dispersing a population of colloidal particles in an aqueous solution including a polymer and a co-dispersant to form a dispersion, subjecting the dispersion to a temperature which causes the polymer to gel.   
   
   
       17 . The method of  claim 16  further comprising removing ionic species from the dispersion. 
   
   
       18 . The method of  claim 17 , wherein the removing step is selected from adding ion-exchange resin or dialyzing. 
   
   
       19 . The method of  claim 16  wherein the polymer is comprised of a partially hydrolyzed poly(vinyl)acetate and the co-dispersant is selected from the group consisting of dimethylsulfoxide, glycerine, ethylene glycol, propylene glycol and triethylene glycol. 
   
   
       20 . The method of  claim 19  wherein the population of colloidal particles comprises substantially monodispersed polymeric particles in a crystalline colloidal array having an average diameter from about 30 nanometers to about 3000 nanometers, and a coefficient of variation of particle diameter of about 15% or less. 
   
   
       21 . The method of  claim 16  wherein the subjecting step includes the temperature of less than about 10 degrees Celsius. 
   
   
       22 . The method of  claim 21  wherein the subjecting step includes the temperature of less than about 0 degrees Celsius. 
   
   
       23 . The method of  claim 22  wherein the subjecting step includes the temperature of less than about −20 degrees Celsius. 
   
   
       24 . A method of storing colloidal particles comprising
 dispersing a population of colloidal particles in an aqueous solution including a polymer and a co-dispersant to form a dispersion, subjecting the dispersion to a temperature which causes the polymer to gel forming a thermo-reversibly gelled colloidal material, wherein   the population of colloidal particles comprises substantially monodispersed polymeric particles in a crystalline colloidal array having an average diameter from about 30 nanometers to about 3000 nanometers, and a coefficient of variation of particle diameter of about 15% or less and   the thermo-reversibly gelled colloidal material freezes only at temperature of less than −20 degrees Celsius.   
   
   
       25 . A method of forming photonic crystal materials wherein the thermoreversible gelation step immobilizes the periodicity of the dielectric constant modulation and where further chemistry is utilized to modify the photonic crystal material for additional applications.